Method for forming photo-defined micro electrical contacts

ABSTRACT

A method of manufacturing a probe test head for testing of semiconductor integrated circuits includes: defining shapes of a plurality of probes as one or more masks; a step for fabricating the plurality of probes using the mask; and disposing the plurality of probes through corresponding holes in a first die and a second die. The step for fabricating the plurality of probes may include one of photo-etching and photo-defined electroforming.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Continuation-In-Part of pending U.S. patentapplication Ser. No. 10/027,146, filed Dec. 20, 2001, which claims thebenefit of U.S. Provisional Patent Application Serial No. 60/323,651,filed Sep. 20, 2001, both of which are incorporated by reference hereinin their entirety.

BACKGROUND OF THE INVENTION

[0002] (1) Field of the Invention

[0003] This invention relates to a method for the manufacture ofminiature micro probes or electrical contacts for use in testingsemiconductor chips.

[0004] (2) Description of the Related Art

[0005] It is known in the art of testing probe cards for electricalcontinuity to perform such tests using probes made by mechanicallyforming a straight piece of fine wire into a desired shape so as toprovide the necessary size and spring force. FIGS. 1-3 show aconventional “Cobra™” probe test head produced by WentworthLaboratories, Inc. of Brookfield, Conn. Such probe heads consist of anarray of probes 64 held between opposing first (upper) 42 and second(lower) 44 dies. Each probe has opposing upper and lower ends. The upperand lower dies 42, 44 contain patterns of holes corresponding to spacingon an integrated circuit contact pad spacing designated herein as lowerdie hole pattern and upper die hole pattern. The upper end of each ofthe probes is retained by the upper die hole pattern, and the lower endof each of the probes passes through the lower die hole pattern andextends beyond the lower die 44 to terminate in a probe tip. Withreference to FIG. 13, there is illustrated the additional inclusion ofmounting film 1301. Mounting film 1301 is typically formed from asuitable polymeric dielectric such as mylar and holds the etched probes81 in place. For Cobra™ style probes, the lower die hole pattern isoffset from that in the upper die 42, and the offset is formed into theprobe such that the probe acts like a spring. Returning to FIGS. 1-3,when the test head is brought into contact with a wafer to be tested,the upper end of the probe remains predominately stationary, while thelower end compresses into the body of the test head. This complianceallows for variations in probe length, head planarity, and wafertopography. The probe is typically formed by swaging or stamping astraight wire to produce the desired probe shape and thickness. Thisswaging process flattens and widens the center, curved portion of theprobe in order to achieve a desired force per mil of probe deflection.

[0006] The lower and upper ends of the swaged area also prevent theprobe from extending too far through the dies. In a conventional probemanufacturing process, the probes are formed from a straight piece ofwire, typically of beryllium-copper alloy. Custom tooling is used foreach probe size and design. The tooling stamps and forms the centerportion of the wire to achieve the desired shape and thickness, therebygenerating a desired spring rate.

[0007] With reference to FIG. 9 there is illustrated cross sectionalrenderings of a wire used in the prior art to produce probes. Crosssection 90 illustrates the generally circular form of the pre-stampedwire. Cross section 91 illustrates the generally elliptical shape of astamped and tooled wire. The cross sectional areas of both cross section90 and cross section 91 are substantially the same. With reference tocross section 91, the stamped wire forming the probe has a width 95 ofapproximately 7 mil (one mil equals 0.001 inch) and a height 97 ofapproximately 1.8 mils. When assembled in a probe head configuration itis preferable to maintain at least a 1 mil separation between theplurality of probes used in the probe head. As a result of width 95being approximately 7 mils and requiring a 1 mil separation,conventional probes arranged in a probe head are typically spaced oneprobe every 8 mils. The wire is then cut to length, and the desiredprobe tip geometry is ground on the end of the probe. The tolerance onthe overall length of the finished probes is +/−0.002″ Because this istoo large a variance between probes for proper testing, the probes areassembled into a probe head and the entire array of probes is lapped toachieve a more uniform probe length.

[0008] Conventional stamping processes used to form probes often resultin residual stresses in the probes which may cause reduced fatigue life.Because these residual stresses can change over time, changes in probestiffness may arise. In addition, changes in the requirements for probesrequire retooling. Such retooling contributes to a high cost for probesmanufactured in such a fashion and require a substantial lead timebefore such probes are available. It is also the case that mechanicallyfashioned probes are more difficult to redesign as their construction isclosely tied to the mechanical means by which they are created.

[0009] There therefore exists a need for a method of manufacturing suchprobes that avoids the problems which arise from mechanical formation.There is further a need for such a method substantially amenable toproducing probes of different designs absent a protracted retoolingprocess.

BRIEF SUMMARY OF THE INVENTION

[0010] One aspect of the instant invention is drawn to a method offabricating a plurality of micro probes comprising the steps of definingthe shapes of a plurality of probes as one or more masks, applying aphotoresist to first and second opposing sides of a metal foil,overlaying one each of the masks on opposing first and second sides ofthe metal foil, exposing the photoresist to light passed through each ofthe masks, developing the photoresist, removing a portion of thephotoresist to expose a portion of the metal foil, and applying anetcher to the surface of the metal foil to remove the exposed portion toproduce a plurality of probes.

[0011] Another aspect of the instant invention is drawn to a method offabricating a plurality of micro probes comprising the steps of:defining the shapes of a plurality of probes as a mask; applying aphotoresist to a side of a first metal material; overlaying said mask onsaid side of said metal first material; exposing said photoresist tolight passed through said mask; developing said photoresist; removing aportion of said photoresist to expose a portion of said first metalmaterial; electroforming a second metal material on said exposedportions of said first metal material; and removing said second metalmaterial to produce a plurality of probes.

[0012] Another aspect of the invention is drawn to a micro probemanufactured according to the aforementioned method wherein the microprobe comprises a probe base having a generally uniform thicknessbounded by a plurality of edges and extending for a substantiallystraight length in a plane, a probe shaft connected to the probe basethe probe shaft of the generally uniform thickness, bounded by aplurality of edges, and extending along a curved expanse within theplane, a probe end connected to the probe shaft the probe end of thegenerally uniform thickness, bounded by a plurality of edges, andextending for a substantially straight distance within the plane thestraight distance being approximately parallel to the straight length,and a scallop running substantially around a periphery comprised of theedges of the probe base, the probe shaft, and the probe end.

[0013] Yet another aspect of the invention is drawn to a probe test headcomprising a first die comprised of first and second opposing planarsurfaces the first die further comprising a pattern of first die holesextending through the first die in a direction perpendicular to both ofthe first and second planar surfaces, a second die comprised of thirdand forth opposing planar surfaces the second die further comprising apattern of second die holes corresponding to the pattern of first dieholes the second die holes extending through the second die in thedirection wherein the third planar surface is arranged in planar contactwith the second planar surface such that the second die holes are offsetfrom the first die holes in a substantially uniform direction, and aplurality of probes one each of the probes extending through one of thefirst die holes and one of the second die holes the probes having asurface finish commensurate with having been formed by electroforming oretching.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a perspective illustration of a probe test head known inthe art.

[0015]FIG. 2 is a perspective illustration of a cross section of a probetest head known in the art.

[0016]FIG. 3 is a cross section of a portion of a probe test head knownin the art.

[0017]FIG. 4 is a front view of a probe of the present invention.

[0018]FIG. 5 is a side view of a probe of the present invention.

[0019]FIG. 6 is an isometric view of a probe of the present invention.

[0020]FIG. 7 is a photograph of a mask of the present invention.

[0021]FIG. 8 is a photograph of a standard probe known in the art and aphoto-defined probe of the present invention.

[0022]FIG. 9 is a cross sectional illustration of a probe known in theart both before and after machining.

[0023]FIG. 10 is a cross sectional diagram of a probe of the presentinvention after etching.

[0024]FIG. 11 is a perspective illustration of the tip of a probe of thepresent invention.

[0025]FIG. 12 is a perspective illustration of the configuration of themasks, the photoresist, and the flat stock of the present inventionprior to etching.

[0026]FIG. 13 is a cross section of a portion of a probe test head ofthe present invention.

DETAILED DESCRIPTION

[0027] The present invention is drawn to a method of manufacturingprobes in a way that provides improved uniformity while lowering themanufacturing cost of the probes. The probes are manufactured using aprocess in which the probes are photo-defined. By “photo-defined” it ismeant that the desired shape of the probes is first specified as animage in graphic form, and the image is used to make a mask having arepeating pattern of the desired probe profile. The mask is then usedalong with a photoresist in a photo-etching or photo-definedelectroforming process, rather than a mechanical stamping processprevalent in the art.

[0028] With reference to FIG. 8, there is illustrated a photo-definedprobe 81 of the present invention and a standard probe 83 known in theart. The desired shape of the probe 81 of the present invention is firstspecified as an image in graphic form, and the image is used to make aglass mask having a repeating pattern of the desired probe profile. FIG.7 illustrates a sample of such a mask 73. Mask 73 is comprised of aplurality of probe shapes 72 and dark spaces 71. The probe shapes 72define the areas corresponding to the photo-defined probes of thepresent invention and are constructed so as to allow light to passsubstantially unimpeded through probe shapes 72. Dark spaces 71 extendpredominantly between probe shapes 72 and serve to substantiallydifferentiate one probe shape 72 from each other probe shape 72 on mask73.

[0029] In a first embodiment of the present invention, the mask 73 isused in a process wherein the probes 81 are etched from thin metal flatstock, typically of Beryllium-Copper alloy. In a second embodiment ofthe present invention, a stainless steel mandrel is formed using themask 73, and the probes 81 are in turn electroformed on the mandrel froma thin metal, typically of Nickel or Nickel-Cobalt alloy.

Embodiment 1—Etched Probes

[0030] With reference to FIG. 12, there is illustrated the probeconfiguration 1205 employed to produce the etched probes of the firstembodiment of the present invention. Flat stock 1201 is a predominantlyplanar sheet of thin metal having opposing planar surfaces. Flat stock1201 has a width corresponding to the desired width of the finishedprobe. A preferred width of the flat stock 1201 is approximately 3 mil.

[0031] A photoresist 1001 is then applied to both opposing planarsurfaces of flat stock 1201. Two identical masks 73 are then fastened toopposing sides of flat stock 1201 with one side of each mask 73 incontact with the photoresist 1001 covering a single side of flat stock1201. The two masks 73 are aligned such that any one feature in eithermask 73 corresponding to an identical feature in the other mask 73 is inexact alignment across an axis perpendicular to the expanse of theplanar surfaces of flat stock 1201. Light is then applied to each mask73 effective to expose the photoresist 1001 disposed between each mask73 and flat stock 1201. Both masks 73 are then separated from probeconfiguration 1205. After exposure of the photoresist 1001 to light, thephotoresist 1001 is developed and rinsed. As a result of rinsing,exposed photoresist 1001 corresponding to a probe shape 72 on mask 73remains bonded to flat stock 1201, while unexposed portions ofphotoresist 1001 corresponding to a dark space 71 is rinsed off of andout of contact with flat stock 1201.

[0032] An etcher is then applied at substantially the same time to bothsurfaces of flat stock 1201. The etcher begins to dissolve flat stock1201 in a direction extending from the outer surfaces of flat stock 1201along an axis perpendicular to the planar expanse of flat stock 1201 anddirected into flat stock 1201 from each opposing planar surface. Oneattribute of applying etcher to a photoresist affixed to a metalsubstrate in order to dissolve the metal substrate is the presence ofunder cutting. As used herein, “undercutting” refers to the tendency ofan etcher applied to dissolve metal to deviate from an etched pathextending perpendicular to the surface to which the etcher was applied.Specifically, the etcher tends to extend outward as it travels into themetal.

[0033] With reference to FIG. 10, there is illustrated the effect onundercutting on the etched probes of the present invention. FIG. 10 is across sectional view of the etched probes of the present invention afterapplying the etcher. As can be seen, the etcher has effectively removedthe metal comprising flat stock 1201 from the area bordered by undercut1005 and etch limit 1007. As is illustrated, undercut 1005 extends froman exterior surface of flat stock 1201 towards the interior of flatstock 1201. Note that undercut 1005 deviates slightly from perpendicularaxis 1009 running perpendicular to the surfaces of flat stock 1201. Etchlimit 1007 is the boundary designating the extent to which the etcherremoves flat stock 1201 up until the etcher is neutralized or otherwiserendered incapable of further etching. Because the etcher etches at asubstantially constant rate and follows a path along undercut 1005deviating from perpendicular axis 1009, the resultant etch limit 1007forms a gently curving boundary. By controlling the amount of time thatthe etcher is exposed to flat stock 1201, it is possible to produce thecross sectional geometry of each probe as illustrated in FIG. 10.

[0034] The resultant superposition of two opposing etch limits 1007results in the presence of sharp protrusions or scallops 1003 extendingaround the perimeter of each etched probe. Note that the distance fromscallop base 1013 to scallop tip 1015 forms the scallop dimension 1011.With reference to FIG. 11, there is illustrated a perspective view of aprobe end 5005. As can be seen, scallop 1003 extends around the edge1107 of the etched probe 81 including probe tip 1101. Outer probe tip1105 is located on opposing sides the flat stock 1201 comprising etchedprobe 81 at the furthest extreme of probe end 5005. Probe tip 1101 canbe seen to extend beyond outer probe tip 1105 as a result of the scallop1003 extending around the terminus of probe end 5005. The resultingextension of probe tip 1101 beyond outer probe tip 1105 allows forbetter contact with electrical circuits when etched probe 81 is in use.

[0035] Removing the unexposed metal results in an array of probesattached at their top end. The array of probes is then chemicallypolished and plated. The probes are then removed from the flat stock1201 and readied for assembly into a probe head. The tops of the probesforming the assembly are lapped while the tips are held referenced to aflat surface to bring the probes to the same length.

Embodiment 2—Electroformed Probes

[0036] In the second embodiment of the present invention, the mask 73,or a negative of the mask 73, is used to form a metal (e.g., stainlesssteel) mandrel for use in electroforming an array of probes 81. In thisembodiment, a photoresist is applied to one side of a stainless steelsurface, and the mask 73 is applied over the photoresist. Light is thenapplied to the mask and exposed portions of the photoresist. Thephotoresist is developed and rinsed leaving patterned open or exposedareas on the stainless steel surface corresponding to the probe shape.The patterned stainless steel surface can now be used as a mandrel forelectroformning.

[0037] During electroforming, the mandrel is placed in a suitable bathand the production or reproduction of the photoresist defined contactsare produced by electrodeposition of a desired thickness of a metalmaterial (e.g., Nickel or Nickel-Cobalt alloy) onto the exposed portionsof the mandrel. The photoresist may then be stripped from the mandrelusing a suitable solvent. The electrodeposited material is subsequentlyseparated from the mandrel as an array of probes attached at their topend. The individual probes are then removed from the array, ready forassembly into a probe head. The tops of the probes forming the assemblyare lapped while the tips are held referenced to a flat surface to bringthe probes to the same length.

[0038] With reference to FIGS. 4-6, there is illustrated the shape of aphoto-defined probe of the present invention as manufactured usingeither the etching or electroforming methods described above.

[0039] With reference to FIG. 5, there is illustrated the basiccomponents of probe 81. Probe base 5001 is a relatively short andstraight expanse connected to probe shaft 5003. Probe shaft 5003 is agently curving expanse of the probe 81 that terminates in the probe end5005. In operation, it is probe end 5005 that comes in contact with thecircuit to be tested. With reference to FIG. 8, as has been described,the photo-defined probes 81 of the present invention are manufactured toa desired configuration absent mechanical stamping or other processeswhich typically result in residual stresses present in the probes 81. Asused herein, “residual stresses” refers to stresses that remain as theresult of plastic deformation. Conventional probes tend to containresidual stresses resulting from the mechanical stamping and machiningemployed to create a desired probe cross-section. These residualstresses serve to limit the functionality of conventional probes in atleast two primary ways. First, residual stresses cause conventionalprobes to exhibit non-uniform resistive forces in response to a seriesof constant deflections administered to the probe over a period of time.As a result, conventional probes used regularly over a period of timetend to suffer from degradations in their ability to supply constantresistive forces to uniform deflections administered over a period oftime. Second, conventional probes comprised of residual stresses aremore likely to break in response to a deflection. In contrast, thephoto-defined probes 81 of the present invention are created from anetching or electroforming process which does not require mechanicalstamping or machining to achieve desired cross sectionalcharacteristics. As a result, the probes 81 do not contain any residualstresses induced as a result of machining or stamping.

[0040] As used herein, “yield strength” refers to the property of aprobe to deflect, or yield, in a predominantly linear direction when aforce is applied while retaining the ability to return to its original,non-deflected state absent the application of a force. The greater theyield strength of a probe, the greater the linear deflection that may beexerted upon the probe prior to the probe reaching its yield point,whereupon the probe will not return to its original shape. Applicantsanticipate that the photo-defined probes of the present inventionexhibit increased yield strength compared to probes formed frommechanical processing. Specifically, Applicants anticipate that thephoto-defined probes may be deflected a linear distance approximately20% greater than that distance through which a conventional probe may bedeflected before reaching the yield point.

[0041] In addition, it is anticipated that the photo-defined probes ofthe present invention will possess improved spring force uniformity overprobes formed in the conventional manner. As used herein, “spring force”refers to the opposing resistive force generated in a probe which isdeflected through a distance. Specifically, it is anticipated that themaximum difference in the spring forces amongst all of the photo-definedprobes in a probe test head will be approximately 20% less than themaximum difference in the spring forces amongst all of the conventionalprobes in a similar probe test head apparatus.

[0042] With reference to FIG. 10, etched probe 81 has a depth 1017 and awidth 1019. Depth 1017 is typically approximately 3 mils while width1019 is typically approximately 1 mil. The electroformed probes 81 canbe made to similar dimensions. Because the photo-defined probes 81(whether etched or electroformed) are considerably narrower thanconventional probes 83, when assembled in a probe head the photo-definedprobes 81 may be assembled spaced approximately every 4 mils whileconventional probes 83 are typically spaced approximately every 8 mils.Because the center-center distance between the photo-defined probes ofthe present invention assembled in a probe head can be as small as 4mils, as opposed to the approximately 8 mils required of conventionalprobes, the photo-defined probes may be used for testing smallerintegrated circuits wherein the distance between contacts on theintegrated circuit wafer is as small as approximately 4 mils.

[0043] In addition, because a plurality of photo-defined probes 81 isfashioned from a single flat stock 1201 (in the case of etching) or froma single electroforming process (in the case of electroforming) using acommon mask 73, each etched probe 81 is substantially similar in itsphysical characteristics to each and every other etched probe 81.

EXAMPLE 1

[0044] The following example details parameters preferable to practicingan embodiment of the present invention. Preferably, there is practiced aplurality of steps including material preparation, photo masking,etching, chemical polishing, plating, and a process of individualizingthe probes thus formed. As used herein, “DI” is a descriptor meaningde-ionized. In addition, as used herein, “UX DI” refers toultrasonically agitated de-ionized water.

[0045] To prepare the material out of which the probes were to beformed, BeCu 17200 Flat stock was cut into squares with side lengthsapproximating four inches. The flat stock was then cleaned withCitra-solv (by Citra-Solv, LLC of Danbury, Conn.)/DI H2O 20 ML/1 L (UX15 Min.). The surface of the flat stock was then air blown dry and theresulting package was then heat hardened in a vacuum for approximatelytwo hours at 600° F.

[0046] Next, the prepared material was photo masked. To accomplish thephoto masking, the material was again cleaned with Clean Citra-Solv/DIH2O 20 ML/1 L (UX 15 Min. ). Next the material was provided a dip coatwith a withdraw rate of 13.3 Sec./1 in. (Shipley SP2029-1) Thinned to 35Zon/Sec. at 21° C. The material was then dried for approximately 30minutes at 90° C. and allowed to cool at room temperature underconditions of greater than fifty percent relative humidity. Next, theprepared surface of the material was exposed to approximately 100milijules 365 nanometer wavelength UV light. The surface exposed to thelight was then developed for approximately 1 min 30 sec (Shipley 303developer, by Shipley Inc. of Newton Mass., at 85° F.). Lastly, theprepared surface was rinsed in cascading DI water for 15 minutes thenair blown dry and stored.

[0047] Next, etching was performed using a Marseco Mod.# CES-24, byMarseco Inc. of Huntington Beach, Calif. Hi-speed circuit etching wasthen performed using Phibro-Tech High Speed Circuit etching solutionwith the following parameter settings:

[0048] Temperature setting 128 deg. F. (act 127 deg. F.)

[0049] Pump speed (Pump #1-45%) (Pump #2-73%)

[0050] Conveyor (11%)

[0051] Oscillation (Normal)

[0052] A foil test piece was then mounted to the carrier and run throughthe etcher. The critical dimensions of the resultant parts created fromthe foil test piece were then measured and adjustments made ifnecessary. After adjustments were made, the remaining foils were runthrough the etcher at 30 sec. intervals.

[0053] Next a chemical polish/bright dip was applied to the probesformed from etching. The probes were submerged in PNA Etch in a 2Lbeaker at 145-150° F. while stirring. The solution was comprised asfollows: Phosphoric Acid  760 ML of a 98% solution Nitric Acid  40 ML ofa 69-70% solution Acetic Acid 1200 ML of a 60% solution

[0054] First, the etch rate was established using a test piece ofmaterial. Next, the probe material was etched to remove 0.0001″ Next thematerial was rinsed in hot DI, in UX DI for approximately 15 minutes anda DI cascade for approximately 2 minutes. Lastly, the probes are ovendried at 100° C. until dry.

[0055] Next, the probes were plated using a Pallamerse ImmersionPalladium 5% solution, by Technic Inc. of Cranston R.I., and a Pdactivator 25% solution manufactured by Technic Inc. and a Vertrelsolvent by Dupont Fluoroproducts of Wilmington, Del. The probes werethen weighed and their weights recorded. The probes were then washed inthe Vertrel solvent for approximately two minutes. Next, the probes wererinsed in DI H₂O for one minute and in a 10% sulfuric acid solution fortwo minutes followed by another two minute rinse in DI H₂O. The probeswere then immersed for 30 seconds in the Technic Pd activator and onceagain rinsed in DI H₂O for 30 seconds. The probes were then immersed for45 minutes in Technic immersion Palladium while stirring slowly, rinsedwith running DI H₂O and dried. The probes were then re-weighed and theirweights recorded.

[0056] Lastly, the probes were individualized. A sample of the probes,preferably five or six probes, is tested to measure the grams ofresistive force generated within each of the probes when deflected fromone to eight millimeters in one millimeter increments. The results onone such test group of probes is illustrated in Table 1. The results ofthe test were used to assess the uniformity of the probes created fromany one initial flat stock as well as conformity to desired properties.The probes were then put in a vile and labeled with tip and shankdimension. TABLE 1 Dim. Force 1^(st) 1^(st) Sample Touch Touch 1 mil 2mil 3 mil 4 mil 5 mil 6 mil 7 mil 8 mil 1 0 .0050 4.80 9.80 12.95 15.6317.86 20.10 21.41 21.72 2 0 .0053 4.50 8.80 12.23 15.21 17.80 19.8121.60 18.02 3 0 .0051 4.80 9.90 13.60 17.00 19.70 21.30 22.31 23.31 4 0.0056 4.91 9.60 13.92 17.70 20.30 22.80 24.80 25.41 5 0 .0045 5.80 11.0014.90 17.30 19.60 21.72 22.22 22.50 6 0 .0053 4.82 8.66 12.23 14.9217.30 19.50 21.26 22.15

[0057] There is therefore provided herein a process for mass producingminiature micro probes or electrical contacts for use in the testing ofsemiconductor chips having the following advantages over theconventional probe manufacturing process. First the method of thepresent invention provides improved uniformity and dimensional accuracybetween the probes. The glass mask determines the geometry of theprobes, eliminating mechanical variances between the probes. As aresult, the stiffness of the probes are more uniform, allowing for abalanced contact force across the array.

[0058] In addition, there are no stresses induced in the probes duringfabrication, resulting in improved probe strength and endurance. Theconventional stamping process results in residual stresses, causingreduced fatigue life. The stresses can change over time, causing changesin probe stiffness.

[0059] The present invention provides for lower cost and lead-time inmanufacturing. Many probes are manufactured simultaneously, and the tipgeometry can be made via the etching or electroforming process ratherthan as a follow-on process step. The polishing and plating processesare also done simultaneously.

[0060] The probe design of the present invention can be easily modified.Where etching is used, the spring rate can be controlled by varying theartwork used to create the glass mask, and by the thickness of the flatmetal stock selected. Where electroforming is used, the spring rate canbe controlled by varying the artwork used to create the glass mask andby controlling the thickness of the electroform. In either case, newdesigns can be made by simply creating a new mask. There is no need forexpensive and time consuming re-tooling.

[0061] Lastly, the etched or electroformed probes produced by the methodfor the present invention do not require a swage to achieve the requiredstiffness. As a result, the probes can be placed closer together,allowing for a denser array.

What I claim is:
 1. A method of fabricating a plurality of micro probescomprising the steps of: defining the shapes of a plurality of probes asa mask; applying a photoresist to a side of a first metal material;overlaying said mask on said side of said first metal material; exposingsaid photoresist to light passed through said mask; developing saidphotoresist; removing a portion of said photoresist to expose a portionof said first metal material; electroforming a second metal material onsaid exposed portions of said first metal material; and removing saidsecond metal material to produce a plurality of probes.
 2. The method ofclaim 1 wherein said first material is stainless steel.
 3. The method ofclaim 1 wherein said second material is selected from one of Nickel andNickel-Cobalt alloy.
 4. A micro probe manufactured according to themethod of claim 1 said micro probe comprising: a probe base having agenerally uniform thickness bounded by a plurality of edges andextending for a substantially straight length in a plane; a probe shaftconnected to said probe base said probe shaft of said generally uniformthickness, bounded by a plurality of edges, and extending along a curvedexpanse within said plane; a probe end connected to said probe shaftsaid probe end of said generally uniform thickness, bounded by aplurality of edges, and extending for a substantially straight distancewithin said plane said straight distance being approximately parallel tosaid straight length; and a scallop running substantially around aperiphery comprised of the edges of said probe base, said probe shaft,and said probe end.
 5. The micro probe of claim 4 wherein said uniformthickness is between 2 mils and 5 mils.
 6. The micro probe of claim 5wherein said uniform thickness is between 3 mils and 4 mils.
 7. Themicro probe of claim 6 wherein said scallop further comprises a scallopbase and a scallop tip.
 8. The micro probe of claim 7 wherein saidscallop base and said scallop tip are separated by a substantiallyuniform distance.
 9. A probe test head comprising: a first die comprisedof first and second opposing planar surfaces said first die furthercomprising a pattern of first die holes extending through said first diein a direction perpendicular to both of said first and second planarsurfaces; a second die comprised of third and forth opposing planarsurfaces said second die further comprising a pattern of second dieholes corresponding to said pattern of first die holes said second dieholes extending through said second die in said direction wherein saidthird planar surface is arranged in planar contact with said secondplanar surface such that said second die holes are offset from saidfirst die holes in a substantially uniform direction; and a plurality ofprobes one each of said probes extending through one of said first dieholes and one of said second die holes said probes having a surfacefinish commensurate with having been formed by electroforming.
 10. Theprobe test head of claim 9 further comprising two spacing covers oneeach of said spacing covers inset into said first and second die. 11.The probe test head of claim 9 wherein each of said plurality of probesis substantially uniform in shape when compared to each other one ofsaid plurality of probes.
 12. The probe test head of claim 9 wherein thelength of each of said plurality of probes is within 0.002 inches ofevery other one of said plurality of probes.
 13. The probe test head ofclaim 12 wherein the length of each of said plurality of probes iswithin 0.001 inches of every other one of said plurality of probes. 14.The probe test head of claim 13 wherein the length of each of saidplurality of probes is within 0.0005 inches of every other one of saidplurality of probes.
 15. A method of manufacturing a probe test head,the method comprising: defining shapes of a plurality of probes as oneor more masks; a step for fabricating the plurality of probes using theone or more masks; disposing the plurality of probes through acorresponding first plurality of holes in a first die, the first dieincluding first and second opposing planar surfaces and the firstplurality of holes extending through the first die between the first andsecond opposing planar surfaces; and disposing the plurality of probesthrough a corresponding second plurality of holes in a second die, thesecond die including third and fourth opposing planar surfaces and thesecond plurality of holes extending through the second die between thethird and fourth opposing planar surfaces.
 16. The method of claim 15,wherein the step for fabricating the plurality of probes using the oneor more masks includes: applying a photoresist to a side of a firstmetal material; overlaying the one or more masks on the side of themetal first material; exposing the photoresist to light passed throughthe one or more masks; developing the photoresist; removing a portion ofthe photoresist to expose a portion of the first metal material;electroforming a second metal material on the exposed portions of thefirst metal material; and removing the second metal material to producea plurality of probes.
 17. The method of claim 15, wherein the step forfabricating the plurality of probes using the one or more masksincludes: applying a photoresist to first and second opposing sides of ametal foil; overlaying at least one of the masks on each of opposingfirst and second sides of the metal foil; exposing the photoresist tolight passed through each of the masks; developing the photoresist;removing a portion of the photoresist to expose a portion of the metalfoil; and applying an etcher to the surface of the metal foil to removethe exposed portion to produce a plurality of probes.
 18. The method ofclaim 15, wherein each probe in the plurality of probes includes: aprobe base having a generally uniform thickness bounded by a pluralityof edges and extending for a substantially straight length in a plane; aprobe shaft connected to the probe base the probe shaft of the generallyuniform thickness, bounded by a plurality of edges, and extending alonga curved expanse within the plane; a probe end connected to the probeshaft the probe end of the generally uniform thickness, bounded by aplurality of edges, and extending for a substantially straight distancewithin the plane the straight distance being approximately parallel tothe straight length; and a scallop running substantially around aperiphery comprised of the edges of the probe base, the probe shaft, andthe probe end.
 19. The method of claim 18 wherein the uniform thicknessis between 2 mils and 5 mils.
 20. The method of claim 19 wherein theuniform thickness is between 3 mils and 4 mils.
 21. The method of claim18 wherein the scallop further comprises a scallop base and a scalloptip.
 22. The method of claim 21 wherein the scallop base and the scalloptip are separated by a substantially uniform distance.